Question

The figure given below represents an experimental set up with a weighing machine to demonstrate a particular process in plants. The experimental set up was placed in bright sunlight. Study the diagram and answer the following questions :

(i) Name the process intended for study.

(ii) Define the above mentioned process.

(iii) When the weight of the test tube (A & B) is taken before and after the experiment, what is observed ? Give reasons to justify your observation in A & B.

(iv) What is the purpose of keeping the test tube B in the experimental set up ?

Answer 1

(i) Transpiration

(ii) It is the lost of water in the form of water vapours from the aerial parts of the plant

(iii) Weight of test tube A will decrease after the experiment because water will be lost from it through the leaves by transpiration. Weight of test tube B will remain same after the experiment because water will not be lost by transpiration as there is no plant in it and nor by evaporation as oil is spread over it, which will not allow evaporation.

(iv) It is a control experiment where the purpose of using test tube B is to compare the level of water in both test tubes.